Generally, a plurality of side keys may be installed on side surfaces of various mobile telecommunication terminals, such as cellular phones and PCS phones, for serving as function keys to subsidize functions of main keys. FIG. 1 is a perspective view of a conventional folder-type mobile telecommunication terminal. FIG. 2 is a partial perspective view of a side key portion of the mobile telecommunication terminal shown in FIG. 1. The mobile telecommunication terminal 1, as shown in FIGS. 1 and 2, comprises a first body 10 housing a main printed circuit board (PCB) 16 and a second body 20 including a liquid crystal display (LCD) panel 21 for displaying various data thereon, wherein the second body 20 is rotatably connected to the first body 10.
A speaker 22 for outputting audio data is provided at one side of the LCD panel 21. A rotatable hinge unit 23 for rotatably connecting the second body 20 to the first body 10 is formed at the other side of the LCD panel 21. A plurality of main keys 11 and a plurality of side keys 14 are respectively disposed on an upper surface and a side surface of the first body 10. A microphone 13 for inputting audio data is provided at a lower end of the first body 10 adjacent to the plurality of main keys 11.
Fixed hinge units 12 for rotatably connecting the second body 20 to the first body 10 are formed at an upper end of the first body 10. A battery 15 for supplying power to the mobile telecommunication terminal is detachably connected to a rear surface of the first body 10.
A plurality of input switches 17 are disposed at a side portion of the main PCB 16. The plurality of input switches 17 are operationally connected to the plurality of side keys 14, respectively, such that when one of the side keys 14 is pressed by a user, a corresponding input switch 17 is activated by the user-pressed side key. Accordingly, the user may use the side keys 14 to input signals into the mobile telecommunication terminal, such as when inputting a signal to adjust a tone during telephonic communication. A key pad 18, made of rubber, and having a plurality of key portions 19 corresponding to the main keys 11, is connected to an upper surface of the main PCB 16. The plurality of key portions 19 are operationally connected to the plurality of main keys, respectively, such that when one of the main keys 11 is pressed by the user, a corresponding key portion 19 is activated by the user-pressed main key.
FIG. 3 is a perspective view of a conventional side key flexible printed circuit board (FPCB) 30. FIG. 4 is a partial perspective view of the side key FPCB 30 shown in FIG. 3, which is connected to the first body 10. The side key FPCB 30 is operationally connected with the side keys 14, such that when the side keys 14 are pressed by the user, the side key FPCB 30 is activated to input signals into the mobile telecommunication terminal. In order to manipulate the side key FPCB 30, the side key FPCB 30 must be structurally supported by a rib 40, which may formed into the first body 10 by injection molding.
FIG. 5 is a schematic view illustrating a general structure of the side key FPCB 30. FIG. 6 is a side view illustrating an installed state of the side key FPCB 30 shown in FIG. 5. A back plate 31 made of stainless steel is attached to one side surface of a double-sided tape 32. A flexible printed circuit (FPC) 33 is attached to the other side surface of the double-sided tape 32. One end of the FPC 33 passes through the rib 40, and is operationally fixed to a portion of the main PCB 16 (FIG. 2) by soldering at soldering point 36. Here, reference numeral 34 represents dimple domes attached to a side surface of the FPC 33 with double-sided tape (not shown) and reference numeral 35 represents a PET film.
The side key FPCB 30 is sensitive to manipulation. Accordingly, under the condition that the back plate 31 made of a hard material is attached to the FPC 33, the rib 40 supports the side key FPCB 30 and controls the manipulation of the FPCB 30.
FIG. 7 is a schematic view illustrating a shape of the rib 40 applied to a straight side key FPCB and used by a mobile communication terminal having straight side surfaces. FIG. 8 is a schematic view illustrating a shape of a rib 50 applied to a straight side key FPCB and used by a mobile telecommunication terminal having curved side surfaces.
Compared to the rib 40 shown in FIG. 7, the rib 50 shown in FIG. 8 requires a large space for the straight side key FPCB 30 to occupy. Thus, an area on the main PCB 16 for mounting components is decreased. Accordingly, it is difficult to apply the straight side key FPCB 30 to the mobile telecommunication terminal having the curved side surfaces. Nonetheless, an attempt to solve the above problem has been proposed wherein a separable straight side key FPCB is applied to the mobile telecommunication terminal having the curved side surfaces.
However, if the separable straight side key FPCB is applied, the number of soldering points are increased from one to two or more, which increases the possibility of connectivity problems. Moreover, data processing using the separable straight side key FPCP is more complicated compared to data processing using a solid straight side key FPCB.
Also, the above straight FPCB 30 has been used in conventional box-shaped mobile communication terminals. But, as circular or curved mobile communication terminals have been put out into the market, a separable tact switch or a plurality of side key FPCBs are used to manipulate the side keys 14 of the terminals. However, due to its lack of reliability, the tact switch is no longer used. Furthermore, when the plurality of side key FPCBs are used, the usable region of the first body 10 is decreased and data processing must be separated.
Accordingly, it is the object of the present invention to provide side key FPCB that overcomes the problems of the related art.